1. Field of the Invention
Exemplary aspects of the present invention generally relate to an image forming apparatus, such as a copier, a facsimile machine, a printer, or a multi-functional system including a combination thereof.
2. Description of the Related Art
Conventionally, there is known an optical writing device employed in an electrophotographic image forming apparatus, which uses an LED head including light emitting diodes to illuminate a photosensitive drum with light. Generally, the LED head is disposed near the photosensitive drum. If the photosensitive drum or peripheral parts need to be removed or replaced, the LED head hinders replacement of these devices. In order to facilitate replacement of these devices, in one approach, the LED head is movable relative to the photosensitive drum.
For example, the LED head is attached to a movable cover provided to the upper portion of the image forming apparatus so that the LED head and the cover move together as a single integrated unit. As the cover is moved to open, the LED head is separated from the photosensitive drum.
In order to facilitate an understanding of the novel features of the present invention, as a comparison a description is provided of a conventional LED-head retainer with reference to FIGS. 10 and 11. As illustrated in FIG. 10, a plurality of LED heads 100 is attached to a cover 300 via head retainers 200. Each of the head retainers 200 includes a link member 200a attached to the cover 300 and a holding member 200b that holds the LED head 100. The link member 200a is rotatably attached to the cover 300. The holding member 200b is rotatably attached to the link member 200a. In other words, each LED head 100 is held by the head retainer 200 with two rotation axes. In this example, when the cover 300 is opened upward, each LED head 100 moves upward together with the cover 300, separating from photosensitive drums 400.
As illustrated in FIG. 11, each head retainer 200 includes a guide rib 500 which is inserted between a rib 600 and an arm 700 serving as guide members provided at an image forming apparatus main body side as the cover 300 is closed. In this configuration, the LED heads 100 are guided towards the photosensitive drums 400 and positioned in place in the width direction of the LED heads 100 (or the horizontal direction in FIG. 11).
Although advantageous, because the head retainer 200 is rotatable freely at two locations, when the guide members of the main body side guide the head retainer 200, the head retainer 200 may not reliably contact the guide members.
In view of the above, there is thus an unsolved need for an image forming apparatus capable of reliably guiding an optical writing head to a proper position.